Field of the Invention PA0 Description of the Prior Art PA0 System Overview PA0 Machine Description PA0 Master/Area Communication System PA0 MACS Optical Link PA0 MACS I/O Instructions and Operational Overview PA0 TABLE 1 PA0 Simultaneous Area Operation PA0 Status Read and Write Commands PA0 TABLE 2 PA0 TABLE 3 PA0 TABLE 4 PA0 Master Controller PA0 Master I/O Interface PA0 Parity Generator PA0 Clock Generator PA0 Shift Controls PA0 Address Decoder PA0 Status Input and Output Control PA0 Interrupt Flip-Flop PA0 Area I/O Interface PA0 Area Controller Operation PA0 Port Structure PA0 Area Microprocessor and Interface PA0 Pseudo-Interrupt Operation PA0 TABLE 5 PA0 TABLE 5A PA0 Machine Clock Interrupt PA0 Real Time Interrupt PA0 Software Description and Organization PA0 State Checker PA0 TABLE 6 PA0 Interrupt Handler PA0 Paper Path Area Controller PA0 TABLE 7 PA0 RDH/ADF Control Console Controller 8 PA0 TABLE 8 PA0 RDH/Platen Servos Controller 10 PA0 TABLE 9 PA0 Master/Servo Software Communications PA0 TABLE 10 PA0 Phase Lock Loop Control PA0 Servo Controller Software PA0 Process Controller 12 PA0 Master/PCR Software Communication PA0 TABLE 11 PA0 TABLE 12 PA0 PCR Software